package com.app.conf;

import lombok.extern.slf4j.Slf4j;
import org.springframework.context.annotation.Configuration;
import org.springframework.stereotype.Component;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.annotation.WebInitParam;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;


/**
 * @Author
 * @Date
 * @Description sql防注入过滤器
 */
@WebFilter(urlPatterns = "/*", filterName = "sqlFilter")
@Configuration
public class SqlFilter implements Filter {

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain)
            throws IOException, ServletException {
        ServletRequest request = servletRequest;
        ServletResponse response = servletResponse;
        // 获得所有请求参数名
        Enumeration<String> names = request.getParameterNames();
        String sql = "";
        while (names.hasMoreElements()) {
            // 得到参数名
            String name = names.nextElement().toString();
            // 得到参数对应值
            String[] values = request.getParameterValues(name);
            for (int i = 0; i < values.length; i++) {
                sql += values[i];
            }
        }
        if (sqlValidate(sql)) {
            throw new IOException("您发送请求中的参数中含有非法字符");
        } else {
            filterChain.doFilter(request, response);
        }
    }

    // 效验
    protected static boolean sqlValidate(String str) {
        String s = str.toLowerCase();// 统一转为小写
        String badStr = "extractvalue|select|update|and|or|delete|insert|truncate|char|into|substr|ascii|declare|exec|count|master|into|drop|execute|table|"
                + "char|declare|sitename|xp_cmdshell|like|from|grant|use|group_concat|column_name|"
                + "information_schema.columns|table_schema|union|where|order|by|"
                + "'\\*|\\;|\\-|\\--|\\+|\\,|\\//|\\/|\\%|\\#";// 过滤掉的sql关键字，特殊字符前面需要加\\进行转义
        // 使用正则表达式进行匹配
        String[] params = badStr.split("\\|");
        for (String p : params) {
            if(s.matches(p))
            {
                return true;
            }
        }
        return false;
    }

    @Override
    public void destroy() {

    }
}
